| The North Silver Bell ore deposit provides a laboratory to conduct comprehensive studies of a yet unmined and culturally uncontaminated porphyry system. Since 1993 Zonge Engineering has sponsored a suite of geophysical surveys over the area including complex resistivity (CR), controlled source audio-frequency magnetotellurics (CSAMT), magnetics (Mag), reconnaissance (vector) induced polarization (RIP), and laboratory rock property measurements. Analysis of data indicates North Silver Bell is best characterized as a broad magnetic low in which resistivity and phase response are primarily a function of alteration assemblages. Lowest resistivities and highest phase responses are associated with areas of substantial phyllic overprinting in which strong to stockwork quartz-sericite-pyrite veinlets predominate. Geophysical discrimination of the supergene enrichment blanket is difficult except in areas of high copper sulfide concentration (... |
